IMTU up-ports vary enormously. As they age they tend to grow, and it's generally not in a way that follows any grand long-term plan. Thus big old stations will tend to look like an asymmetrical assemblage of random starship construction parts.
Newer ones look more orderly. It's fairly common for lower TL worlds to use 'planetoid hulls'. As they often use a rock that's much bigger than they initially need, these can absorb considerable growth before they need to start growing random growths externally, though docking towers and shipyards for major ships will tend to appear stuck on apparently random parts of the rock over time.
There will be exceptions, of course. These will be either nice new stations, or ones owned by an entity that's good at making and sticking to long-term plans (a megacorp or perhaps the Imperial Navy). I would expect most to have a base form that's both inexpensive and that has a large surface area, because a great deal of an up post's utility is in dealing with spaceships and that means docks and cargo bay and access to them, and so on. Ease of maintenance and of managing traffic control works against things like dispersed or close structures, with their many small parts and odd angles, etc. Therefore such well-designed and managed up-ports will tend to be boxes or cylinders. Low TL worlds with questionable artificial gravity might used spun wheels, but gravitics are so common that this would be rare.
